This invention relates to the production of metallic articles.
It is known that within limited temperature ranges and at limited strain rates certain alloys may be processed to give a very fine grain structure and thereafter be capable of deforming superplastically. Providing that the processed structure is sufficiently fine these alloys then exhibit abnormally high plasticity under relatively low loads when compared with the same alloys that do not possess extremely fine grain sizes. It is also known that the phenomenon of superplastic deformation may be employed to enable the relatively cheap manufacture of articles from metal blanks which have been processed to have extremely fine grain sizes.